Allow manual @import of Sass partials

[loljoho]

Whenever I scaffold with this generator I've ended up adding this single line.

I hate having everything in a single index.scss so I create partials with filenames prefixed by _ (e.g. _variables.scss, _mixins.scss) which often need to be loaded in a specific order.

My index.scss often ends up looking something like this:

@import 'core/styles/variables';
@import 'core/styles/mixins';
// etc, etc...

/**
 *  Do not remove this comments bellow. It's the markers used by wiredep to inject
 *  sass dependencies when defined in the bower.json of your dependencies
 */
// bower:scss
// endbower

/**
 *  Do not remove this comments bellow. It's the markers used by gulp-inject to inject
 *  all your sass files automatically
 */
// injector
// endinjector

By ignoring the _-prefixed partials along with index.scss in the styles.js Gulp file, this allows the developer to @import whichever files he or she wishes in whatever order, rather than leaving it up to the rest of the Gulp tasks.

In the project on which I am currently working, this changes the original styles.js at line 19 from:

  var injectFiles = gulp.src([
    path.join(conf.paths.src, '/app/**/*.scss'),
    path.join('!' + conf.paths.src, '/app/index.scss')
  ], { read: false });

...to this:

  var injectFiles = gulp.src([
    path.join(conf.paths.src, '/app/**/*.scss'),
    path.join('!' + conf.paths.src, '/app/**/_*.scss'),
    path.join('!' + conf.paths.src, '/app/index.scss')
  ], { read: false });

Sorry, still new to contributing--let me know if there's anything I could have done better.

Cheers :)

[Swiip]

Sorry, if you have to change this everytime but it seams not generic enough to be distributed to everyone. I'm sure, every one has it's way of doing this.